Q25 of 26 Page 1

An aromatic compound ‘A’ of molecular formula C7H6O2 undergoes a series of reactions as shown below. Write the structures of A, B, C, D and E in the following reactions :


OR


(a) Write the structure of main products when benzene diazonium chloride reacts with the following reagents :


(i) H3PO2 + H2O


(ii) CuCN/KCN


(iii) H2O


(b) Arrange the following in the increasing order of their basic character in an aqueous solution:


C2H5NH2, (C2H5)2NH, (C2H5)3N


(c) Give a simple chemical test to distinguish between the following pair of compounds:


C6H5 – NH2 and C6H5 – NH – CH3


A : C6H5COOH (Benzoic acid)



B : C6H5NH2 (Aniline)



(because amide reacts with bromine water to form Aniline)


C : C6H5NHCOCH3 (N-phenyl ethanamide)



(because aniline reacts with acitic anhydride it produces N-phenyl ethanamide)


D : C6H5CH2NH2 (Benzylamine)



(When benzyl amide reacts with LiAlH4, then through reduction process carbonyl compounds changes into produces Benzyl Amine).


E: C6H4(Br)3 (NH2) (2, 4, 6 – Tribromoaniline)


When Aniline reacts with Bromine water(Br2 aq.) then through the substitution process, it produces 2, 4, 6 – Tribromoaniline.



OR


(a)


(i)



When benzene diazonium chloride reacts with mild reducing agents such as hypophosphorous acid, it undergoes a nitrogen displacement reaction. Here, the benzene diazonium chloride is reduced to benzene. H3PO2 itself is oxidized to phosphorous acid. Nitrogen formed escapes as gas.


(ii)



Benzene diazonium chloride on reaction with CuCN/KCN, undergoes nitrogen displacement reaction. The presence of Cu(I) ion helps the introduction of the nucleophilic CN- ion. The product formed is Benzonitrile, with the escape of nitrogen as gas. The reaction is known as Sandmeyer reaction.


(iii)



The hydrolysis of benzene diazonium chloride gives Phenol as a product with the evolution of nitrogen gas. When the diazonium salt solution is heated and the temperature is allowed to rise to 283°K, the nucleophile OH- is introduced, forming phenol.


(b) C2H5NH2 < (C2H5)3N < (C2H5)2NH


+I effect of three C2H5 groups increases the enormous availability of lone pair of electrons on the nitrogen atom than +I effect of 2 ethyl groups. Thus the order of basicity is I < III < II.


(c) C6H5—NH2 (Primary amine) and C6H5—NH—CH3 (Secondary amine) can be distinguished by Hinsberg’s test. In this test amines are treated with Hinsberg reagent, benzenesulphonyl chloride (C6H5SO2Cl). Primary amines reacts with this reagent to form N-alkylbenzene sulphonyl amide which is soluble in alkali but secondary amines gives sulphonamide which is insoluble in alkali.


More from this chapter

All 26 →
22

Write the names and structures of the monomers of the following polymers:

(i) Terylene


(ii) Buna-S


(iii) Neoprene


 23

Seeing the growing cases of diabetes and depression among young children, Mr. Chopra, the principal of one reputed school organized a seminar in which he invited parents and principals. They all resolved this issue by strictly banning junk food in schools and introducing healthy snacks and drinks like soup, lassi, milk, etc. in school canteens. They also decided to make compulsory half an hour of daily physical activities for the students in the morning assembly. After six months, Mr. Chopra conducted the health survey in most of the schools and discovered a tremendous improvement in the health of the students.

After reading the above passage, answer the following questions:


(i) What are the values (at least two) displayed by Mr. Chopra ?


(ii) As a student, how can you spread awareness about this issue?


(iii) Why should antidepressant drugs not be taken without consulting a doctor?


(iv) Give two examples of artificial sweeteners.


 24

(a) Account for the following :

(i) Acidic character increases from HF to HI.


(ii) There is a large difference between the melting and boiling points of oxygen and sulphur.


(iii) Nitrogen does not form pentahalide.


(b) Draw the structures of the following:


(i) ClF3


(ii) XeF4


OR


(i) Which allotrope of phosphorus is reactive and why ?


(ii) How are the supersonic jet aeroplanes responsible for the depletion of ozone layer ?


(iii) F2 has lower bond dissociation enthalpy than Cl2. Why ?


(iv) Which noble gas is used in filling balloons for meteorological observations ?


(v) Complete the following equation :



 26

For the hydrolysis of methyl acetate in aqueous solution, the following results were obtained :

(a) Show that it follows pseudo first order reaction, as the concentration of water remains constant.


(b) Calculate the average rate of reaction between the time interval 10 to 20 seconds.


(Given: log 2 = 0.3010, log 4 = 0.6021).


OR


(a) For a reaction A + B → P, the rate is given by Rate = k[A][B]2


(i) How is the rate of reaction affected if the concentration of B is doubled ?


(ii) What is the overall order of reaction if A is present in large excess ?


(b) A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90% completion of this reaction.